Gas separation technology is needed in various industries. One gas separation of particular interest is commercial scale carbon dioxide (CO2) gas separation. Currently, there are two methods of CO2 gas separation in commercial use.
One method is cryogenics that involves cooling the entire gas mass to be separated, whereupon the CO2 gas preferentially condenses and is collected. Cryogenics is considered prohibitively expensive, due to the high energy consumption involved in cooling the large mass of gas, with some potential for economic use at very high CO2 gas concentrations of up to 75%. Most effluent streams contain 10-40% CO2 gas, and therefore cryogenics is not considered economically viable for CO2 gas separation.
The second method of CO2 gas separation in commercial use is amine scrubbing, which involves exposing the gas mass to be separated to a solution of an amine. However, amine scrubbing is currently used only on a small commercial scale and is poorly scalable to the large scales needed for CO2 gas capture from, for example, power plant emissions; because of its high energy consumption, low capacity, and high capital and operating costs.
Other methods of CO2 gas separation are in development but also suffer from the deficiencies associated with the cryogenics and the amine scrubbing methodologies noted above. That is, other methodologies in development, such as solvation as with methanol in the Rectisol process for acid gas removal, and membrane separators suffer from low economic viability due to high energy consumption, poor selectivity, low capacity and poor scalability to large commercial scales.